Writing apparatus and method of manufacture

ABSTRACT

A stylus and its method of manufacture for forming an image on the recording medium of a printing apparatus having the structure of a substrate upon which a plurality of conductors are etched or printed. The writing edge of the stylus containing the pin electrodes formed by the conductors has a chip of wear resistant or hard material laminated to the substrate to prevent excessive wear of the pin electrodes. Alternately, the substrate itself is made of a wear resistant or hard material to prevent wear of the pin electrodes.

United States Patent 1191 Ring Feb. 26, 1974 54] WRITING APPARATUS ANDMETHOD or 2,661,998 12/1953 Pessel 346/139 c MANUFACTURE 2,892,6666/1959 Parker.... 346/74 CH 3,119,919 1/1964 Pratt 346/74 SB [75]Inventor: a d g, Rochester, NY 3,307,198 2/l967 Morgan 346/74 ESAssigneez Xerox Corporation, Rochester, NDY. 3,643,263 2/1972 Fowler346/74 ES Filedi 1971 Primary ExaminerTerrell W. Fears [21] Appl. No.:213,761

Related US. Application Data [57] ABSTRACT [62] Division of Sen 14,138Feb. 5 1970 A stylus and its method of manufacture for forming anabandoned; image on the recording medium of a printing apparatus havingthe structure of a substrate upon which a 52 [1.5. CI. 346/74 ES,346/139 plurality of conductors are etched or printed The 51 Int. Cl.G0ld 15/24 writing edge of the stylus containing the p electrodes 5Field Search 34 74 s 39 c 74 E, 74 5 formed by the conductors has a chipof wear resistant 34 74 SB, 74 5 74 CH or hard material laminated to thesubstrate to prevent excessive wear of the pin electrodes. Alternately,the 56 Ref n e Ci substrate itself is made of a wear resistant or hardmaterial to prevent Wear Of the electrodes.

2,404,975 7/1946 Mathes 346/139 C 6 Claims, 6 Drawing Figures 1 WRITINGAPPARATUS AND- METHOD OF MANUFACTURE This isa division of applicationSer. No. 14,138, filed Feb 25", 1970 and now abandoned.

This invention relates to printing apparatus and more particularly to awear resistant or hard stylus for a printing apparatus and a method formaking such a stylus.

BACKGROUND OF THE INVENTION In electrographic recording an electrostaticcharge is deposited directly on an insulating or recording medium in a.pattern or. image corresponding to the charges applied to the pinelectrodes. Generally, the

, period of time. In order to form a visible rendering of theelectrostatic image it is necessary to develop the imagewithlelectroscopic powder or toner. A toneris selected so that it willbe charged to a polarity opposite to that of the electrostatic image.When this toner is deposited upon the charged surface, the image exertsa force of attraction on the toner and retains the toner in the chargedareas. Subsequently, the toner may be fused into the recording mediummaking a permanent record. v r g In most styli printing apparatus thestyli have limited life due to the wear of the pin electrodes as theyare swept across the recording medium. Consequently, the styli must bereplaced periodically adding to the expense of operation of the printer.Many attempts have been made to obtain styli which have longer life inorder to reduce frequent replacement. However, these attempts haveeither resulted in complete failure or in increased fabrication costs.

One way of obtaining long lasting styli is to make the conductors ashard as possible. This approach creates problems of fabrication becausehard materials such as tungsten, tungsten carbide, nickel-tungsten, hardchromium, stainless steel or beryllium-copper are difficult to place onetched copper conductors. Attempts to do so result in cracking of theplating on the writing tips or in shorting of the electrode conductorsbecause of the close spacing of the etched pattern.

Accordingly, it is an objectof this invention to provide a stylus for aprinting apparatus which has long life, is inexpensive and easy tofabricate.

It is another object of this invention to increase the life of a stylusemployedv in a printing apparatus by a novel method of manufactureinvolving overlaying the writing edge with a wear resistant or hardmaterial.

It is yet another-object of this invention to increase the life of astylus by forming the writing edge on a wear resistant or hardsubstrate.

BRIEF DESCRIPTION OF THE INVENTION The stylus made in accordance withthe invention is a copper pattern etched or printed on glass epoxymatei'ial, a commonly known printing circuit board sub.- stance. To thisconfiguration the chip of wear resistant or hard material is laminatedat the writing edge to form the long lived stylus. Other variations offabricating a long lived styli include etched or printed conductorson asubstrate of wear resistant or hard material. Styli made in conformitywith the invention are not only inexpensive and simple to fabricate buthave a useful life of more than double conventionally fabricated styli.

These and further objects of the present invention will be more fullyunderstood by reference to the description which follows and theaccompanying drawings wherein:

FIG. 1 is a vastly simplified view of an electrographic printingapparatus utilizing a stylus made in the manner of the invention,

FIG. 2 isv a left side elevational view of theimprovedstylus showing awear resistant'chip laminated to the writing edge,

FIG. 3 is a right side elevational view of the stylus showing the spacedconductors on the substrate,

FIG. 4 is a view taken along the line 4-4 of FIG. 2 showing the detailsof the stylus writing edge,

FIG. Sis a view taken along the line 5-5 of FIG. 4 showing thelaminations on the substrate, and

FIG.'6 is a view similar to FIG. 5 showing electrodes deposited upon theinsulating material.

Referring now to the drawing for a more detailed description of thepresent invention and specifically to FIG. 1, a stylus designated 11 isshown mountedon a molded base or support member 9. Base member 9 is inturn mounted upon carriage assembly 33 in a socket (not shown) whichconveys electrical signals to the conductors of the stylus. Carriageassembly 33 carrying stylus l1 traverses laterally in slot 34 of guidebar 32 by movement of cable 31 to which the carriage assembly isconnected. Cable 31 is frictionally engaged to rotate about drive pulley35 and idler pulley 37. Drive pulley 35 is driven by motor 38 throughshaft 36 so that the carriage assembly 33 moves in printing alignmentwith recording medium 15 from left to right and in synchronism withinput data to stylus 11 and the engagement of motor 38. That is, stylus11 prints data on recording medium 15 controlled in time and space byinput circuits not shown but conventional in the art such as a charactergenerator and a timing pulse generator. The recording medium 15, asstated above, may be a plastic coated paper, pre-dried paper or anysuitable dielectric sheet. The writing surface of platen 21 also servesas a backing electrode so that an electric field is established betweenthe pin electrodes of the stylus and the platen depositing a charge onthe recording medium in the form of marks or dots. The platen isgenerally maintained at ground potential but may have a bias voltage andthe pin electrodes may have a voltage applied to them in the range of600-1000 volts. Therecording medium may be advanced over guide roller 14by drive rollers 12 and 13 in a stepwise manner so that when thecarriage assembly reaches the farthest right hand position and moves tothe left hand position, the recording medium has advanced a sufficientamount so that a new line of information may be recorded. Means such aslimit switches at the lateral extremes of the carriage positions may beprovided to signal the end of thetraverse of the carriage at the lateralextremes.

In the foregoing explanation of the stylus and printing apparatus it isassumed that stylus 1 l impresses an electrostatic image on therecording medium..In such 7 utilized wherever a long lived writingstylus is needed and is not intended to be restricted to sole use inelectrographic recording devices.

Referring to FIGS. 2-5, there is shown in more detail the improvedstylus of the invention. The molded base 9 of stylus 11 is made of aninsulating material into which the terminal end of the stylus. ispermanently mounted. The writing end 10 of stylus 11 is spaced from theterminal end 5 and base 9 by a reduced shaft portion 4. The writing endis generally L-shaped having pin electrodes 1 aligned to simultaneouslycontact the recording medium. Part 2 is a ceramic chip which islaminated onto substrate 3 at the writing edge 8 and provides the wearresistant or hard surface when aligned with pin electrodes 1. 7

FIG. 3shows in elevation a plurality of conductors 6 which may be etchedor printed on substrate 3 and which run along the length of thesubstrate to form the writing end 10 and terminal end 5. Although thenumber of conductors and pin electrodes are shown as seven, it isunderstood that a matrix of pin electrodes exceeding that number may beobtained by stacking several basic substrates together. Such aconstruction of pin electrodes in a matrix is within the purview of theinvention.

FIG. 4 is a view taken along the line 4--4 of FIG. 2 and shows thedetail of the writing edge 8. It is to be understood from FIG. 4 thatthe rate of wear is determined solely by the wear resistant or hardmaterial and not the pin electrodes which the wear resistant materialprotects. I

FIG. 5 is a viewtaken along the line 5--5 of FIG. 4

' and shows in detail the structure of the writing edge.

Reference number 4 is a layer of insulating material such as an acrylicplastic resin known as l-lumiseal made by Columbia Technical Corp., ofWoodside, N. Y. that electrically isolates pin electrodes 1 from eachother and prevents sparking. Substrate 3 may be a plastic such as aglass epoxy G- l 0 made by General Electric Co., Syracuse, N. Y. usedconventionally in printed circuit fabrication. 0n the side opposite pinelectrodes 1 of substrate 3 is a chip 2 ofwear resistant or hardmaterial which may comprise an aluminum oxide or any other suitable wearresistant material. Aluminum oxide chip 2 has a thickness of 0.005 inchi 0.001 inch, a

width of 0.093 inch 2*: 0.0l0 inch and a length of 0.125

inch i 0.010 inch.

FIG. 6 is a view similar to FIG. 5 showing the details of an embodimentin which insulating material 63 overlays the ceramic substrate 62 andelectrodes 61 are in turn deposited upon the insulating material 63.Electrodes 61 are insulated from each other by insulating material 63.The materials used for the electrode6l,

4 r r the substrate 62, and the insulating layer63 maybe the same as thematerial. described above with regard to FIG. 5.

A Wear resistant or hard material accordingto the in I vention means amaterial having a degree of hardness shown by its resistance to cutting,scratching or abrasion. The MohI-Iardness Scale is a system in which allsolid substancesare grouped in order ofincreasing hardness so that thehardness of any particular substance may be expressed by a number. Onthe Moh' Hardness Scale tale is assigned the integer l and diamond, thehardest material, is assigned the integer l5. Tungsten carbide isassigned the number l2 and fused, alumina the number 13. In practice ofthe invention the wearresistant material is chosen such that itshardness is greater than the hardness of the conductor material.

The wear resistant stylus of the invention is inexpensive and easy tofabricate. Several styli may be made simultaneously by printing oretching copper patterns having a terminal end and a pin electrode end ona G-l0 glass epoxyprinted circuitboard material. The

next step is to coat the board with a dielectric material such asplastic resin. The coating should then be allowed to cure and may bebaked in an oven for approximately one-half hour. However, the cure timeandtemperaturedep'endupon the specific plastic resin utilized.

The. outlines including the writing edge of the styli are then separatedand machined. The plastic body or base is then molded around theconnector end of the stylus. Heat is next applied to the tip or writingend of the stylus to bend it away from the main body portion and than apiece of wear resistant ceramic such as aluminum oxide is laminated witha suitable glue to the back, side of the writing edge of the stylus.Finally, the conti- V nuity of conductors of the stylus is checked forelectrical shorts and high voltage breakdown. Where pinelectrode'matrices are to be fabricated several of the substrates formedas described above may be stacked one upon the other in registration. 7

Other methods of fabrication may include depositing conductors on aceramic substrate or etching patterns on a thin glass epoxy substratelaminated to a harder substrate made of a ceramic or a carbide. In thesemethods of fabrication the substrate itself is the wear resistantmaterial.

From the foregoing, a stylus fabricated to have a long life and use in aprinting apparatus has been described.

What is claimed is:

1. An electrographic printing apparatus wherein a charged imagedeveloped by the application of electroscopic toner is formed on ainsulated recording medium which advances as a line of print is layeddown by a laterally moveable carriage assembly, said recordind mediumand carriage assembly moving in response to a signals from a controlsource comprising;

a support member mounted upon said carriage assembly,

a writing member having one end mounted upon said support member and afree end spaced from said fixed end,

a plurality of conductors insulated from each other running the lengthof said writing member, and attached thereto, said conductors formingpin electrodes at the free end of said writing member, which initiallycontact said recording medium and means on the opposite side and spacedfrom the pin electrodes, but attached to said free end of said writingmember, for eventually resisting wear to said pin-electrodes.

2. Apparatus according to claim 1 wherein said means for resisting pinelectrode wear comprises chip means made of aluminum oxide.

3. Apparatus according to claim 1 wherein said means for resisting pinelectrode wear comprised chip means made of tungsten carbide.

4. An electrographic printing apparatus wherein an electrostatic imagedeveloped by the application of electroscopic marking particles isformed on an insulative recording medium which advances as a line ofprint and is laid down by a laterally movable carriage assembly, saidrecording medium and carriage assembly moving in response to signalsfrom a control source comprising:

a stylus including a substrate made of ceramic material,

an insulating layer attached to one side of said substrate,

at least one electrode deposited on said insulating layer, saidelectrode having a writing tip which initially contacts said recordingmember,

chip means attached to the side of said substrate opposite and spacedfrom said writing tip for reducing wear thereof.

5. Structure according to claim 4 wherein said insulating layercomprises a layer of epoxy glass.

6. An 'electrographic printing apparatus wherein an electrostatic imagedeveloped by the application of electroscopic marking particles isformed on an insulative recording medium which advances as a line ofprint and is layed down by a moveable carriage assembly, said recordingmedium and carriage assembly moving in response to signals froma sourcecomprising:

a substrate,

at least one electrode in contact with said recording medium, on onesurface of said substrate adjacent one end thereof, and

a chip of wear resistant material at a position, initially removed fromcontact with said recording medium, and on the opposite side and spacedfrom said electrode, on another surface of said substrate adjacent saidone end.

1. An electrographic printing apparatus wherein a charged imagedeveloped by the application of electroscopic toner is formed on ainsulated recording medium which advances as a line of print is layeddown by a laterally moveable carriage assembly, said recordind mediumand carriage assembly moving in response to a signals from a controlsource comprising; a support member mounted upon said carriage assembly,a writing member having one end mounted upon said support member and afree end spaced from said fixed end, a plurality of conductors insulatedfrom each other running the length of said writing member, and attachedthereto, said conductors forming pin electrodes at the free end of saidwriting member, which initially contact said recording medium and meanson the opposite side and spaced from the pin electrodes, but attached tosaid free end of said writing member, for eventually resisting wear tosaid pin-electrodes.
 2. Apparatus according to claim 1 wherein saidmeans for resisting pin electrode wear comprises chip means made ofaluminum oxide.
 3. Apparatus according to claim 1 wherein said means forresisting pin electrode wear comprised chip means made of tungstencarbide.
 4. An electrographic printing apparatus wherein anelectrostatic image developed by the application of electroscopicmarking particles is formed on an insulative recording medium whichadvances as a line of print and is laid down by a laterally movablecarriage assembly, said recording medium and carriage assembly moving inresponse to signals from a control source comprising: a stylus includinga substrate made of ceramic material, an insulating layer attached toone side of said substrate, at least one electrode deposited on saidinsulating layer, said electrode having a writing tip which initiallycontacts said recording member, chip means attached to the side of saidsubstrate opposite and spaced from said writing tip for reducing wearthereof.
 5. Structure according to claim 4 wherein said insulating layercomprises a layer of epoxy glass.
 6. An electrographic printingapparatus wherein an electrostatic image developed by the application ofelectroscopic marking particles is formeD on an insulative recordingmedium which advances as a line of print and is layed down by a moveablecarriage assembly, said recording medium and carriage assembly moving inresponse to signals from a source comprising: a substrate, at least oneelectrode in contact with said recording medium, on one surface of saidsubstrate adjacent one end thereof, and a chip of wear resistantmaterial at a position, initially removed from contact with saidrecording medium, and on the opposite side and spaced from saidelectrode, on another surface of said substrate adjacent said one end.